Example embodiments of the inventive concept relate to a light emitting diode, and in particular, to a flip-chip light emitting diode with a sub-mount and a method of fabricating the same.
A light emitting diode (LED), one of P-N junction diodes, is a semiconductor device, which is configured to emit monochromatic light under a forward bias condition using an electroluminescence effect, and a wavelength of light to be emitted therefrom is determined a bandgap energy (Eg) of a material used in the LED. Infrared and red LEDs have been mainly used in an initial stage of LED technology, until the fact that a blue LED can be realized using GaN was shown by Shuji Nakamura of Nichia Chemical Industries Ltd., in 1993. The GaN-based blue LED, in conjunction with the previously-prepared red and green LEDs, enables to realize a white LED, in that white color can be realized by combining red, green and blue lights.
To increase marketability of an LED device, it is necessary to increase a light emitting efficiency and a lifetime of the LED device. However, due to a difference in refractive index between GaN and air, only a portion of light generated in an active layer can be emitted to the outside. Accordingly, most of blue LEDs have an external quantum efficiency of about 54%, but several technologies are being suggested to increase the light emitting efficiency of LEDs.
Graphene, a carbon allotrope, is a two-dimensional atomic-scale honeycomb lattice made of sp2 bonded carbon atoms. The graphene has a very stable chemical structure and a very high mobility (e.g., higher than that of silicon by about 100 times or more). Further, the graphene has high optical transmittance and excellent thermal/mechanical properties. Accordingly, various researches are being conducted to utilize the technical merits of graphene.